A Statistical Analysis of the Occurrences of Critical Waves and Water Levels for the Management of the Operativity of the MoSE System in the Venice Lagoon

2021 ◽  
Author(s):  
Giuseppe R. Tomasicchio ◽  
Gianfausto Salvadori ◽  
Letizia Lusito ◽  
Antonio Francone ◽  
Alessandra Saponieri ◽  
...  
Keyword(s):  
Statistical Analysis ◽  
Venice Lagoon ◽  
Water Levels

scholarly journals Delimitation of flood areas based on a calibrated a DEM and geoprocessing: case study on the Uruguay River, Itaqui, southern Brazil

2019 ◽  
Vol 19 (1) ◽  
pp. 237-250 ◽  
Author(s):  
Paulo Victor N. Araújo ◽  
Venerando E. Amaro ◽  
Robert M. Silva ◽  
Alexandre B. Lopes
Keyword(s):  
Statistical Analysis ◽  
Flood Hazard ◽  
Satellite Image ◽  
Water Levels ◽  
Calibration Model ◽  
Southern Brazil ◽  
Temporal Series ◽  
Vertical Accuracy ◽  
High Flood ◽  
Uruguay River

Abstract. Flooding is a natural disaster which affects thousands of riverside, coastal, and urban communities causing severe damage. River flood mapping is the process of determining inundation extents and depth by comparing historical river water levels with ground surface elevation references. This paper aims to map flood hazard areas under the influence of the Uruguay River, Itaqui (southern Brazil), using a calibration digital elevation model (DEM), historic river level data and geoprocessing techniques. The temporal series of maximum annual level records of the Uruguay River, for the years 1942 to 2017, were linked to the Brazilian Geodetic System using geometric leveling and submitted for descriptive statistical analysis and probability. The DEM was calibrated with ground control points (GCPs) of high vertical accuracy based on post-processed high-precision Global Navigation Satellite System surveys. Using the temporal series statistical analysis results, the spatialization of flood hazard classes on the calibrated DEM was assessed and validated. Finally, the modeling of the simulated flood level was visually compared against the flood area on the satellite image, which were both registered on the same date. The free DEM calibration model indicated high correspondence with GCPs (R2=0.81; p<0.001). The calibrated DEM showed a 68.15 % improvement in vertical accuracy (RMSE = 1.00 m). Five classes of flood hazards were determined: extremely high flood hazard, high flood hazard, moderate flood hazard, low flood hazard, and non-floodable. The flood episodes, with a return time of 100 years, were modeled with a 57.24 m altimetric level. Altimetric levels above 51.66 m have a high potential of causing damage, mainly affecting properties and public facilities in the city's northern and western peripheries. Assessment of the areas that can potentially be flooded can help to reduce the negative impact of flood events by supporting the process of land use planning in areas exposed to flood hazard.

Effect of Moisture and Incubation Time on Ochratoxin A Production by an Isolate of Aspergillus ochraceus

1970 ◽  
Vol 53 (1) ◽  
pp. 89-91
Author(s):  
A F Schindler ◽  
Stanley Nesheim
Keyword(s):  
Statistical Analysis ◽  
Moisture Content ◽  
Ochratoxin A ◽  
Incubation Time ◽  
Maximum Yield ◽  
Water Levels ◽  
Aspergillus Ochraceus ◽  
Ambient Temperatures ◽  
Incubation Periods ◽  
Transfer Needle

Abstract Experiments were conducted to determine the culture requirements that would insure a probability of high ochratoxin production with a given isolate. Experiments at ambient temperatures (72 ± 2°F) determined the levels of the two most readily controlled variables, time and moisture content, during the growth of a high toxin-producing isolate (M298) of Aspergillus ochraceus. Tests were conducted in 2.8 L - Fernbach flasks containing 100 g shredded wheat and inoculated with spores on a transfer needle. Amounts of ochratoxin A/flask were determined by comparison against standards on TLC after chloroform extraction. Statistical analysis showed a relation between ochratoxin yield, water levels, and incubation periods. A water level of 40–70 ml/flask with an incubation period of 19-21 days at ambient temperatures should give a near to maximum yield of ochratoxin A.

scholarly journals Statistical Analysis of the Stability of Rock Slopes

2019 ◽  
Vol 7 (3) ◽  
pp. 60 ◽  
Author(s):  
Marcel van Gent ◽  
Ermano de Almeida ◽  
Bas Hofland
Keyword(s):  
Statistical Analysis ◽  
Physical Model ◽  
Model Tests ◽  
Water Levels ◽  
Test Series ◽  
Length Effect ◽  
Wave Flume ◽  
Physical Model Tests ◽  
Erosion Area ◽  
The Stability

Physical model tests were performed in a wave flume at Deltares with rock armoured slopes. A shallow foreshore was present. At deep water, the same wave conditions were used, but by applying different water levels, the wave loading on the rock armoured slopes increased considerably with increasing water levels. This allowed an assessment of the effects of sea level rise. Damage was measured by using digital stereo photography (DSP), which provides information on each individual stone that is displaced. Two test series were performed five times. This allowed for a statistical analysis of the damage to rock armoured slopes, which is uncommon due to the absence of statistical information based on a systematic repetition of test series. The statistical analysis demonstrates the need for taking the mean damage into account in the design of rock armoured slopes. This is important in addition to characterising the damage itself by erosion areas and erosion depths. The relation between damage parameters, such as the erosion area and erosion depth, was obtained from the tests. Besides tests with a straight slope, tests with a berm in the seaward slopes were also performed. A new method to take the so-called length effect into account is proposed to extrapolate results from physical model tests to real structures. This length effect is important, but is normally overlooked in the design of rubble mound structures. Standard deviations based on the presented model tests were used.

scholarly journals Statistical Analysis and Trend Detection of the Hydrological Extremes of the Danube River at Bratislava

2021 ◽  
Vol 906 (1) ◽  
pp. 012101
Author(s):  
Veronika Bacová Mitková
Keyword(s):  
Statistical Analysis ◽  
Anthropogenic Activities ◽  
Water Levels ◽  
Danube River ◽  
Trend Detection ◽  
The Danube River ◽  
Natural Processes ◽  
The Past ◽  
Hydrological Extremes ◽  
Measured Water

Abstract The territory of the Danube River Basin is one of the most flood-endangered regions in Europe. The flow regime conditions of the Danube River are continually changing. These changes are the result of natural processes and anthropogenic activities. In the present study, we focused on the statistical analysis and trend detection of the hydrological extremes of the Danube River at Bratislava. This paper firstly analyses the changes in correlation between water levels of the Danube River at Bratislava and Kienstock. Studied period of 1991-2013 included one or three hour measured water levels of the Danube River at Bratislava and Kienstock and shorter periods (1991–1995, 1999–2002, and 2004—2013) were selected for identification of the water level changes at Bratislava. One of the factors that recall the necessity to establish empirical - regression relationships was increasing of water levels of the Danube River at Bratislava (due to sediments accumulation at Bratislava). The results of the analysis indicated an increasing of water levels corresponding to the same flood discharges observed in the past. We also can say that travel time of the Danube floods between Kienstock and Bratislava did not change significantly during the analysed period. In the second part of the paper, we have identified changes in commonly used hydrological characteristics of annual maximum discharges, annual discharges and daily discharges of the Danube River at Bratislava during the period of 1876–2019. We examined whether there is a significant trend in discharges of the Danube River at Bratislava.

A STUDY OF FAECAL BACTERIA IN THE RIVER KYMI (SOUTH EAST FINLAND)

1967 ◽  
Vol 13 (8) ◽  
pp. 1087-1096 ◽  
Author(s):  
Seppo Niemeiä ◽  
Erkki Tirronen
Keyword(s):  
Statistical Analysis ◽  
Water Level ◽  
High Temperatures ◽  
Selective Adsorption ◽  
High Water ◽  
Water Levels ◽  
River Temperature ◽  
Clay Particles ◽  
Faecal Bacteria ◽  
Faecal Streptococci

Bacteriological observations made on samples taken monthly from the River Kymi over a two year period (June 1964–May 1966) were subjected to statistical analysis. The ratios of numbers of coliforms to those of faecal streptococci (C/F) were found to vary significantly with both the river temperature and water level. High C/F values were associated with high temperatures and high water levels. The former of these findings is probably attributable to the multiplication of coliforms in the river. It is suggested that the latter could arise from more efficient homogenization of coliform aggregates by increased turbulence at high water or from selective adsorption of streptococci by suspended clay particles.

scholarly journals Delimitation of Flood Areas Based on Calibrated DEM and Geoprocessing: Case Study on Uruguay River, Itaqui City, Southern Brazil

2018 ◽  
Author(s):  
Paulo Victor N. Araújo ◽  
Venerando E. Amaro ◽  
Robert M. Silva ◽  
Alexandre B. Lopes
Keyword(s):  
Statistical Analysis ◽  
Flood Hazard ◽  
Satellite Image ◽  
Ground Surface ◽  
Water Levels ◽  
Calibration Model ◽  
Southern Brazil ◽  
Temporal Series ◽  
Flood Level ◽  
Uruguay River

Abstract. Flooding is a natural disaster which affects thousands of riversides, coastal and/or urban communities causing severe damages. River flood mapping is the process of determining inundation extents and depth by comparing historic river water levels with ground surface elevation referenced. This paper aims to map flood geohazard areas under the influence of the Uruguay River, Itaqui city (Southern Brazil), using calibration Digital Elevation Model (DEM), historic river level data and Geoprocessing techniques. The annual maximum for years of 1942 to 2017, of fluviometric temporal series records of Uruguay River were linked to Brazilian Geodetic System using geometric levelling and submitted the statistical analysis. The DEM was calibrated with Ground Control Points (GCP) of high vertical accuracy based on post-processed high-precision GNSS surveys. Using the temporal series statistical analysis results, was assessed the spatialisation of flood hazard classes on the calibrated DEM and validated. Finally, was visually compared the modelling of the simulated flood level versus flood area on satellite image, which both were registered on the same date. The free DEM calibration model indicated high correspondence with GCPs (R2 = 0.81; p 

Coastal flooding protection will change salt-marsh sedimentation dynamics

2021 ◽  
Author(s):  
Davide Tognin ◽  
Andrea D'Alpaos ◽  
Marco Marani ◽  
Luca Carniello
Keyword(s):  
Salt Marsh ◽  
Sea Level Rise ◽  
Sea Level ◽  
Storm Surge ◽  
Sedimentation Rate ◽  
Urban Areas ◽  
Storm Surges ◽  
Venice Lagoon ◽  
Water Levels ◽  
Sedimentation Dynamics

&lt;p&gt;Coastal wetlands lie at the interface between submerged and emerged environments and therefore represent unique yet delicate ecosystems. Their existence, resulting from complex interactions between hydrodynamics and sediment dynamics, is challenged by increasing rates of sea-level rise, lowered fluvial sediment input as well as an increasing anthropogenic pressure. The future survival of these peculiar morphologies is becoming even more complicated, because of the construction and planning of coastal defence structures designed to protect urban areas from flooding. Important examples are the flood protection systems built to protect New Orleans (USA), the river Scheldt Estuary (The Netherlands) and Venice (Italy). In this context, understanding the physical processes on which coastal marshes are grounded and how engineering measures can alter them is of extreme importance in order to plan conservation interventions.&lt;/p&gt;&lt;p&gt;To understand marsh sedimentation dynamics in flood-regulated environments, we investigated through field observations and modelling the effect of the storm-surge barrier designed to protect the city of Venice, the so-called Mo.S.E. system, which has in fact become operational since October 2020.&lt;/p&gt;&lt;p&gt;Sedimentation measurements in different salt marshes of the Venice lagoon carried out in the period October 2018-October 2020 show that more than 70% of yearly sedimentation accumulates during storm-surge conditions, despite their short duration. Moreover, the sedimentation rate displays a highly non-linear increase with marsh inundation intensity, due to the interplay between higher water levels and greater suspended sediment concentration. Barrier operations during storm surges to avoid flooding of urban areas will reduce water levels and marsh inundation. Therefore, we computed sedimentation in a flood-regulated scenario for the same observation period, using the relation we obtained between tidal forcing and sedimentation rate. Our results show that some occasional closures during intense storm surges (70 hours/year on average) suffice to reduce the yearly sedimentation of the same order of magnitude of the relative sea-level rise rate experienced by the Venice lagoon during the last century (2.5 mm/y).&lt;/p&gt;&lt;p&gt;We conclude that storm-surge barrier operations can dangerously reduce salt-marsh vertical accretion rate, thus challenging wetland survival in face of increasing sea-level rise.&lt;/p&gt;

scholarly journals [Waders and seabirds (Charadriiformes) nesting along the north-eastern Adriatic coastline (Veneto and Friuli-Venezia Giulia) in 2008-2014: abundance, trends and major conservation issues]

2019 ◽  
Vol 88 (2) ◽  
pp. 33-41 ◽  
Author(s):  
Francesco Scarton ◽  
Emiliano Verza ◽  
Carlo Guzzon ◽  
Paolo Utmar ◽  
Giacomo Sgorlon ◽  
...  
Keyword(s):  
Abundant Species ◽  
Venice Lagoon ◽  
Water Levels ◽  
Common Tern ◽  
Fish Farms ◽  
The North ◽  
Ne Italy ◽  
The Common ◽  
Sandwich Tern ◽  
Friuli Venezia Giulia

[In 2008-2014 wader and seabird nesting pairs were censused along the 220-km long coastline of the NE Adriatic Sea, in the Veneto and Friuli-Venezia Giulia regions (NE Italy). Fourteen species were regularly breeding, with an annual mean of 20,610 pairs (±1553, 1 SD). The most abundant species was the Yellow-legged Gull (about 13,400 pairs on average, 65% of the whole population of the study area), followed by the Common Tern (1670 pairs, 8.1%) and Common Redshank (1525 pairs, 7.4%). The whole population of waders and seabirds increased with an annual rate, estimated with the TRIM software, of +0.8%, with a greater increase (+4.3%) if the Yellow-legged Gull was not included. Twelve species were stable or increasing; only the yellow-legged gull (-1%) and the common redshank (-2.4%) were decreasing. The populations of several species exceed 10% of those estimated for the whole of Italy; those of the Eurasian Oystercatcher, Common Redshank and Sandwich Tern are among the most important in the whole Mediterranean. On average, about 8860 pairs (43%) nest in the Venice lagoon, 6,400 pairs (31%) in the Po Delta, 5100 pairs (25%) in the Friuli-Venezia Giulia lagoons. Among nesting habitats, semi-natural (such as the fish farms) and man-made sites (dredge islands) make each year about 70% of the nesting pairs. Saltmarsh islets host large numbers of Common Redshank and Sandwich Tern, while along the beach zone the only abundant species are the Yellow-legged Gull and the Eurasian Oystercatcher. The major conservation threats observed in the study area were the erosion of littoral islands, the uncontrolled occurrence of sunbathers along the beaches, the vegetation overgrowth at dredge islands, the increasing frequency of saltmarsh submersion by high tides, the strong fluctuations of water levels inside the fish farms.] [Article in Italian]

scholarly journals Long term trends and breeding parameters of Gull-billed Tern Gelochelidon nilotica in three Italian coastal sites

2020 ◽  
Vol 89 (2) ◽  
Author(s):  
Marcello Grussu ◽  
Francesco Scarton ◽  
Emiliano Verza ◽  
Roberto G. Valle
Keyword(s):  
Venice Lagoon ◽  
Water Levels ◽  
Strong Increase ◽  
Sudden Increase ◽  
Fish Ponds ◽  
Lagoon Of Venice ◽  
Fish Farms ◽  
Breeding Parameters ◽  
Salt Pans ◽  
Po Delta

Between 2001 and 2018 colonies of Gull-billed Tern were monitored in large wetland complexes of Veneto (lagoon of Venice and the Northern Po Delta) and Sardinia (western and southern) regions. Most of the colonies settled in man-made structures such as islets, levees, dams, located inside fish farms, fish ponds and salt pans. Laying took place around half May until early June (Veneto), with eggs occurring in the nests until half July (Sardinia). Colonies had 3-230 pairs, with several instances of isolated pairs; colonies were mono- or plurispecific, with other Charadriiformes. The number of eggs per clutch was 2.6±0.6 (N=111, 1 SD) in the Venice lagoon, 2.6±0.6 (N=182) in the Po delta, 2.3±0.70 (N=1007) in Sardinia; hatched eggs were 2.2±0.6 (N=111), 2.0±0.7 (N=182) and 1.7±0.67 (N=40) per nest, respectively. The most important cause of breeding failure was due to flooding of nesting sites, due to the rapid increase of water levels inside fish farms and salt pans. During the 2001-2018 years, the Gull-billed Tern nested regularly in Sardinia, whereas in the Po Delta the first nesting occurred in 2001 and in the lagoon of Venice in 2008. The whole population ranged between 34 and 417 pairs until 2017 (223.6±113.4, N=17), with a sudden increase up to almost 1,000 pairs in 2018; the overall trend is of strong increase (p<0.01), with an annual rate of 10.5%.

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